Alkylation of hydrocarbons



Patented Nov. 21, 1944 V UNITED STATES PATENT OFFICE.

ALKYLATION F HYDROCARBOITS Frank H. Bruner, Beacon, N. Y., assignor to The Texas Company, New York, N. Y., a corporation of Delaware No Drawing. Original application May 4, 1939,

Serial No. 271,746.

Divided and this application February 4, 1943, Serial No. 474,720

6 Claims. (c1. 260-6834) This invention has to do with the alkylation of hydrocarbons by the union of paraflin and olefin hydrocarbons.

This is a division of co-pending application,

atoms, by reacting isoparaflins with oleflns in the presence of a catalyst.

The invention broadly contemplates reacting olefin and isoparaffin hydrocarbons in the presence of a liquid catalyst comprising a boron trifluoride-water complex which can be expressed by the formula BFs.nH2O.

More specifically, the invention comprises reacting olefin hydrocarbons with isoparaflln hydrocarbons in the presence of a liquid comprising essentially BFa.nHzO, Where n preferably has the value of 1 to 1.5. g

It has been known to use boron trifluoride as a catalyst in the polymerization of olefin hydrocarbons. It has also been proposed to use this compound in the presence of a metallic substance, such as nickel.

It has also been proposed to use boron trifluoride and nickel in conjunction with hydrogen fluoride or water or with both for the alkylation of normally gaseous paraflin. hydrocarbons with normally gaseous olefins. This operation, however, has involved using the boron trifluoride and the hydrogen fluoride in the gaseous phase wherein these gases, along with the hydrocarbon gas, have been passed over the metal catalyst.

The present invention, in contradistinction, involves the employment of aboron trifluoride and water complex in the form of a liquid and which does not require the presence'of metallic substances, such as nickel, to effect the alkylation reaction.

Early workers and text-books have referred to the solution obtained by passing BFa into water as hydrofluoboric acid. Boris acid, H3303 was considered a by-product of the preparation. However, it has been found recently that boric acid, itself, reacts with BFa to form a hydroxy-fiuoboric acid which would indicate that a solution of BF; in water is a much more complex solution than formerly believed. Commercial hydrofluoboric acid is available as an aqueous solution, having a specific gravity of approximately 1.2 and containing only 40% of HBF4, the remainder being water.

The preferred liquid of the present invention is prepared by passing BFs intowater until a saturated solution is obtained which has a gravity V of about 1.77. This liquid is further distinguished from commercial hydrofluoboric acid and dilute solutions of BF: in water inthat it is a very efiective catalyst for alkylation of lsoparaflins with olefins, even to the extent of alkylating isobutane with ethylene. 10 In the preparation of the catalyst, boron trifluoride is passed into water, maintained at around room temperature, until no more of the com pound is absorbed. Boron trifluoride reacts almost instantaneously with water with the initial production of a flocculent precipitate of boric acid and the probable formation of hydrofiuoboric acid according to the following equation:

Upon passing additional BFa into the solution the precipitate gradually disappears with the production of a solution, which finally becomes saturated with boron trifluoride. The resulting solution is a slightly cloudy liquid and apparently 26 substantially anhydrous. This saturated solution of BF3 and H20 has anapproximate composition of 21% B20 and 79% BF3 by weight correspond-, ing to an equimolecular mixture of BF: and H20. The exact reaction products are not known but by 80 using equimolecular quantities of BF3 and H20 the following equations containing possible products may be written:

2BF3 +2H2O HBF4 +HBF2 (OH) 2 Hydro- Dihydroxyfiuoboric fiuoboric acid] acid BF3+H20 HBF3(OH) Monohydroxyfiuoboric acid These equations are not to limit the scope of the reaction of BF: and H20 but are to illustrate possible active ingredients. It is possible that any of the hydrofiuoboric or hydroxyfiuoboric acids formed in the reaction might dissociate to form HF and/or BFa molecules dissolved in the other constituents.

This saturated solution of BFs in H2O upon dilution with more than 10% H2O becomes substantially ineffective in its ability to catalyze alkylation. This ratio of'BFz in H2O corresponds to a composition of BF3.1 HzO, so that the critical composition range is BF3.1H2O to BF3.1 H2O, or a complex containing from 21% to 29% H20 by weight, some of which above 21 may be water 68 of dilution.

ing the complex of BF: in H20, but solutions, such as commercial hydrofiuoboric acid, commercial hydrofluoric acid, etc.,. and pure compounds, such as boric acids, hydroxyfluoboric acids, etc., maybe used as absorbents for BF: to form hydroand/or hydroxy-compounds of boron and fluorine in essentially an anhydrous state, or containing only a small proportion of water within the oritical concentration set forth above. These liquid acid catalysts of this invention are hereinafter referred to in the description and claims as a boron trifluoride-water complex" or BFaJlHzO, where n has a value ranging from about 1 to 1.5.

Like concentrated sulphuric acid, it functions as a catalyst in the liquid phase, giving substantially similar results to those obtained with sulphuric acid in the alkylation of C3 and C4 olefins. It is superior to sulphuric acid as an alkylation catalyst at higher temperatures of the order of 100 to 150 F., because at these temperatures it does not act as an oxidizing agent. This nonoxidizing character is of substantial advantage as regards obtaining complete recovery of the catalyst from the reaction products.

The invention will be understood further from the following examples descriptive of batch type liquid phase operations, using as the catalyst the anhydrous liquid BFhJHzO as prepared above:

Example 1 2,363,116 The catalyst preparation isnot limitedtoform-. a grams or 198% of the olefin charged. Ninety-f three volume per cent of this liquid product distilled below 311 F. and had abromine number of 1.0.

Example 4 195 grams of the catalyst and 335 grams of isobutane were charged to the reaction vessel and this product boiled below 234 F.

Into an agitated mixture containing 190 grams oi the catalyst and 301 grams of isobutane, 99 grams of isobutylene were charged in 30 minutes, the reaction mixture being stirred during an additional 30 minutes. The reaction temperature was held at about 120 F. The reaction mixture thereafter was removed and the reacted hydro carbons separated from the catalyst and stabilized to separate C4. and lighter hydrocarbons, giving a yield of total liquid products of 192.8%

by weight on the basis of the olefin charged.-

The total liquid products were fractionated to produce a fraction having an end point of 311 F. The fraction so obtained amounted to 164.0% by weight based on the olefin charged. An identical experiment was made, except for employing a reaction temperature of 75 F. In this case the yield of total liquid products amounted to 187.0% based on the olefin, and the yield of 311 F. end point fraction amounted to 147.8% based on the olefin charged.

Example 2 fin; and the yield of the 311 F. end point fraction was 116.3%. based on the olefin charged. The reduced yields in this example are attributed in part to less eflicient agitation.

Example 3" A mixture of 335 grams of isobutane and 220 grams of catalyst was heated to 112415 F. and agitated while 68 grams of propylene were added over a period of one hour. Stirring and heating were continued for an additional hour. The stabllized liquid product obtained amounted to 135 Example 5 A hydrocarbon mixture was termed consisting of about 7.5% ethylene, 13.3% propylene, 14.2% C4 olefins, 17% isobutane, 42.4% propane, 1.5% ethane, 3% normal butane, and 11% pentane. 173 grams of this mixture were added to an agitated mixture of 335 grams of isobutane and 180 grams of catalyst maintained at a temperature of around 69 to 75 F. Stirring was continued for an additional hour. The stabilized liquid prodnot obtained amounted to 115 grams or 190% by weight .of the olefins charged. The gas discharged from the reaction vessel was essentially saturated. .74=% of the liquid product distilled below 311 F.

While batch type experiments have been described above, it is contemplated that continuous operations involving concurrent, countercurrent, or a combination of concurrent and countercurrent fiow may be employed, the reaction being carried out in either a single or a plurality of stages, as may be desired.

It is advantageous to operate in a manner so as to maintain a substantial excess of isoparafiin within the reaction zone. For example, the ratio of isoparaflin to olefin may be from one to six or more parts by weight of isoparamn to one part by weight of olefin.

The unreacted parafiin hydrocarbons can be separatedfrom the reaction products and recycled through the reaction zone. The hydrocarbon feed may comprise normally liquid saturated and unsaturated hydrocarbons, or a mixture of normally liquid and normally gaseous hydrocarbons. The olefin feed may comprise either pure orselectediractions from cracked or polymer gasolines. Likewise, it is contemplated that the paraflin feed may comprise normal as well as isoparafiin hydrocarbons.

It is contemplated that the catalyst is efiective for the alkylation with isoparaifins of alcohols, ethers and alkyl halides.

Operations may be carried out under atmospheric, sub-atmospheric or superatmospheric pressure, but, preferably, under sufficient pressure to maintain the reacting materials in the liquid phase at the temperature of reaction. The temperature of reaction may range from 60 F.

or lower to 150 F., but preferably between F. and F. I

It is also contemplated that where the reaction is carried out in a plurality of stages split feed of the olefin may be employed, charging a portion of the olefin hydrocarbons to each of a plurality of stages in the reaction system.

In the parent application Serial No. 271,746, there is claimed isoparafin-olefin alkylation with aseauc 3 a catalyst comprising a boron fluoride-water complex. In the present application, there is claimed isoparafiin-olefin alkylation with a catalyst composition prepared only from HF, H40 and BFz, such as by utilizing commercial or aqueous hydrofluoboric or hydrofluoric acid as the absorbent for BF; to produce the catalyst in essentially an anhydrous state, or with only a limited amount of water within the effective alkylation range.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the pirit and scope thereof and therefore only uch limitations should be imposed as are indicated in the appended claims.

I claim:

1. A process for the production of normally liquid saturated hydrocarbons which comprises reacting at least one parafflnic hydrocarbon containing at least one tertiary carbon atom per molecule with at least one olefinic hydrocarbon under alkylation conditions in the presence of a catalyst composition prepared only from HF, 1120, and BFa.

2. A process for the production of normally liquid saturated hydrocarbons which comprises reacting at least oneparafllnic hydrocarbon containing at least one tertiary carbon atom per molecule with at least one monopleflnic hydrocarbon under alkylation conditions in the presence of a catalyst composition prepared by saturating an aqueous hydrogen fluoride solution with boron fluoride at about room temperature.

3. A process as in claim 2 wherein the paramnic component contains isobutane.

4. A process as in claim 2 wherein the reac- 10 tion i carried out continuously with vigorous agitation and under sufllcient superatmospheric pressure to maintain the reaction mixture in the liquid phase.

5. The method of producing high anti-knock 15 hydrocarbons which comprises alkyiating an isoparafiin with an olefin under alkylation conditions in the presence or a catalyst composition prepared by absorbing BF: in aqueous HF to convert the same to essentially an anhydrous go state. 

